Generally, a clothes treating apparatus having a drying function, such as a washing machine or a clothes dryer, serves to dry laundry having been completely washed and dehydrated, by introducing the laundry into a drum, by supplying hot blast into the drum, and then by evaporating moisture from the laundry.
Hereinafter, the clothes treating apparatus will be explained with taking a clothes dryer as an example. The clothes dryer includes a drum rotatably installed in a body and having laundry introduced thereinto, a driving motor configured to drive the drum, a blowing fan configured to blow air into the drum, and a heating means configured to heat air introduced into the drum. The heating means may use high-temperature electric resistance heat generated from an electric resistance, or combustion heat generated from gas combustion.
Air exhausted from the drum is in a state of a middle temperature and a high humidity due to moisture of the laundry inside the drum. According to a method for processing the air of a middle temperature and a high humidity, the clothes dryer may be classified into a condensation type (circulation type) and an exhaustion type. The condensation type clothes dryer is configured to condense moisture included in the air of a middle temperature and a high humidity, by circulating and cooling the air into a temperature less than a dew point through a condenser, without exhausting the air to the outside. And, the exhaustion type clothes dryer is configured to directly exhaust the middle temperature-high humidity air having passed through the drum to the outside.
In the case of the condensation type clothes dryer, the air has to be cooled into a temperature less than a dew point so as to condense the air exhausted from the drum. And, the air has to be heated by the heating means before being re-supplied into the drum. Here, the air may have the loss of its thermal energy while being cooled. In order to heat the air to a temperature high enough to perform a drying process, required is an additional heater, etc.
In the case of the exhaustion type clothes dryer, it is also required to exhaust the air of a middle temperature and a high humidity to the outside, to introduce external air of a high temperature, and to heat the external air into a desired temperature by the heating means. Especially, high-temperature air exhausted to the outside includes thermal energy transmitted by the heating means. However, the thermal energy is exhausted to the outside, resulting in lowering of the thermal efficiency.
In order to overcome these problems, being proposed is a clothes treating apparatus capable of enhancing the energy efficiency by collecting energy required to generate hot blast, and energy exhausted to the outside without being used. As one example of the clothes treating apparatus, a clothes treating apparatus having a heat pump system is being recently introduced. The heat pump system is provided with two heat exchangers, a compressor and an expander, and enhances the energy efficiency by collecting energy of exhausted hot blast and by re-using the energy to heat air supplied into the drum.
More concretely, the heat pump system is provided with an evaporator at an exhaustion side, and with a condenser at a suction side near the drum. And, the heat pump system transmits thermal energy to a refrigerant through the evaporator, and transmits thermal energy of the refrigerant to air introduced into the drum through the condenser, thereby generating hot blast with using abandoned energy. Here, the heat pump system may further include a heater configured to re-heat air heated while passing through the condenser.
This heat pump system has to maintain a steady state during a drying process so as to enhance the energy efficiency. Accordingly, a state of the heat pump system has to be continuously checked, and each component has to be controlled based on the checked state of the heat pump system so as to maintain a steady state.